This invention relates generally to powder handling apparatus and methods, and more particularly to an automated system for quickly transferring quantities of powder material from one or more sources to one or more destination receptacles.
Automated powder dispensing systems are used in many laboratory and commercial applications. In the pharmaceutical industry, for example, such systems are used to fill capsules with small but accurate doses of drugs, typically using gravimetric or volumetric techniques. These systems suffer various disadvantages, including an inability to handle a wide range of particulate materials at optimal speeds and accuracies, particularly when very small doses are involved (e.g., 20 mg or less). Further, the operation of conventional systems tends to crush the particles being handled.
Automated powder handling systems also have application to combinatorial (high-throughput) research, such as combinatorial catalysis research where catalyst candidates are evaluated using various screening techniques known in the art. See, for example, U.S. Pat. No. 5,985,356 to Schultz et al., U.S. Pat. No. 6,004,617 to Schultz et al., U.S. Pat. No. 6,030,917 to Weinberg et al., U.S. Pat. No. 5,959,297 to Weinberg et al., U.S. Pat. No. 6,149,882 to Guan et al., U.S. Pat. No. 6,087,181 to Cong, U.S. Pat. No. 6,063,633 to Willson, U.S. Pat. No. 6,175,409 to Nielsen et al., and PCT patent applications WO 00/09255, WO 00/17413, WO 00/51720, WO 00/14529, each of which U.S. patents and each of which PCT patent applications, together with its corresponding U.S. application(s), is hereby incorporated by reference in its entirety for all purposes.
The efficiency of a catalyst discovery program is, in general, limited by rate-limiting steps of the overall process work flow. One such rate-limiting step has been the mechanical pretreatment and handling of catalyst candidates after synthesis but before screening. U.S. application Ser. No. 902,552, filed Jul. 9, 2001 by Lugmair, et al., published Feb. 7, 2002 as Pub. No. U.S. 2002/0014546 A1, and assigned to Symyx Technologies, Inc., incorporated herein by reference in its entirety for all purposes, is directed to more efficient protocols and systems for effecting the mechanical treatment of materials, and especially, mechanical treatment of catalysis materials such as heterogeneous catalysts and related materials. The disclosed protocols provide an efficient way to prepare catalysis materials having a controlled particle size for optimal screening. However, the handling and transfer of such powders from one location to another as they are prepared for screening and ultimately delivered to the screening device (e.g., a parallel flow reactor) is not addressed in detail.
It is, therefore, an object of this invention to provide for more efficient protocols and apparatus for the handling of powder in an automated manner without subjecting the particles to crushing forces or other conditions which might change the mechanical or chemical characteristics of the particles (e.g., particle size distribution).
In general, the apparatus of this invention is for aspirating and dispensing powder. The apparatus comprises a hopper having one or more powder transfer ports and one or more suction ports adapted for connection to one or more sources of suction to establish an upward flow of air or other gas through the one or more transfer ports. The apparatus also includes a gas flow control system for varying the upward flow through the one or more transfer ports to have different velocities greater than 0.0 m/s. One such velocity is an aspirating velocity for aspirating powder into the hopper through at least one of the one or more transfer ports to form a fluidized bed of powder in the hopper above the at least one transfer port. Another velocity is a dispensing velocity less than the aspirating velocity but sufficient to maintain fluidization of the bed while allowing powder from the bed to gravitate through at least one of said one or more transfer ports for dispensing into one or more destination receptacles.
The present invention is also directed to a method of transferring powder from one or more sources to one or more destination receptacles. The method comprises the steps of establishing an upward flow of air or other gas through one or more transfer ports of a hopper, and maintaining the upward flow at an aspirating velocity sufficient to aspirate powder into the hopper from at least one of the one or more sources through at least one of the one or more transfer ports to form a fluidized bed of powder in the hopper above the at least one transfer port. The method also includes the step of reducing the velocity of the upward flow of air or other gas to a dispensing velocity less than said aspirating velocity to dispense powder from the hopper by allowing powder from the fluidized bed to gravitate through at least one of the one or more transfer ports into at least one of the one or more destination receptacles.
In another aspect, the method comprises the steps of establishing an upward flow of air or other gas through one or more transfer ports of a hopper, and varying the upward flow through the transfer port to have different velocities greater than 0.0 m/s. These velocities include an aspirating velocity for aspirating powder into the hopper from at least one of the one or more sources through at least one of the one or more transfer ports to form a fluidized bed of powder in the hopper above the at least one transfer port, and a dispensing velocity less than the aspirating velocity but sufficient to maintain fluidization of the bed while allowing powder from the bed to gravitate through at least one of the one or more transfer ports for dispensing into at least one of the one or more destination receptacles.
Other objects and features will be in part apparent and in part pointed out hereinafter.